208 LABYRINTHODONTS. 



The portion of the superior maxillary bone contains the anterior 

 part of the single row of small teeth, and the base of one of the great 

 anterior tusks, which ranges in the same line with the other teeth, 

 but is directed obliquely backwards ; the small serial teeth pro- 

 ject more vertically from the alveolar margin of the jaws and 

 are slightly inclined outwards. In a few places the contiguous 

 teeth are present, but throughout the greater part of the series there 

 is alternately a tooth and an empty socket. The sockets are shallow, 

 and are so closely arranged, that, although the alveolar series in the 

 present fragments is but two inches, three lines in extent, it con- 

 tains thirty-one sockets. The large anterior fang is three times 

 the size of the first of the serial teeth which succeeds it ; and the rest 

 gradually diminish as they recede backwards, so that the eighth tooth, 

 counting the sockets from the first, is little more than half a line in 

 diameter at its base ; beyond this the teeth are of equal size. Each 

 of the serial teeth is slender in proportion to its length, and gradually 

 diminishes from the middle of the crown to the apex, which is not 

 very acute where entire ; a linear pulp-cavity is continued along the 

 centre of the tooth nearly to the apex. The transverse section of 

 the base is elliptical, its smallest diameter being in the axis of the 

 jaw ; that of the apical two thirds of the tooth is circular ; the basal 

 third is finely fluted, the rest of the tooth is smooth. The outer wall 

 of the socket is very thin, and is confluent with the fluted base of 

 the tooth. From the flatness and thinness of the maxillary bones, the 

 sockets of the teeth are necessarily shallow. The length of the com- 

 mon sized serial teeth is about two lines, their greatest diameter one 

 third of a line ; the diameter of the base of the large anterior tusk 

 is two lines and a half. 



The whole of the under surface of the fossil was covered by the 

 sandstone matrix, but the fractured margin, opposite the alveolar 

 border, exhibited the edge of a thin plate of bone, uninterrupted in 

 the longitudinal extent, and forming the floor of a wide and shallow 

 nasal cavity, thus affording a strong indication that the Lahyrinthodon 

 breathed air like the higher reptiles. That the bony palate extended 

 as far in the transverse as in the longitudinal extent was indicated 

 by the projecting base of a fractured conical tooth, twice the size 



